[Death of myocardiocytes and destruction of their structures during embryonic histogenesis]

By means of light and electron microscopy, death of cardiomyocytes and their structures has been studied in the myocardium of chick (the 4th-20th days of incubation) and in rat (the 14th-20th days of embryogenesis) embryos. The same processes have been studied after a single and repeated injections of insulin and 5-fluorauracyl to the chick embryos (into the air chamber of the egg). In the myocardium of the chick and rat embryos atrophy of some muscle cells takes place as a demonstration of histogenetic (physiological) death characterized by changes in nucleo- and cytoplasm according to the "dark" type. Under the effect of 5-fluorauracyl the same type of cardiomyocyte death is observed; differences with the control are but quantitative ones. When the chick embryo is affected with cytotoxic concentrations of insulin, together with histogenetic death of the cardiomyocytes (the "dark" type) the death according to the "light" type also takes place. Under the effect of both insulin and 5-fluorauracyl the destructive processes in the cardiomyocytes are manifested greater than in the control. This is a morphological manifestation of certain disturbances in processes of physiological restoration at the cellular level.